Billions of years ago, Georgian Bay Mnidoo Gamii Biosphere (GBB) was covered by glaciers over two kilometres thick. These glaciers shaped and formed the rocks that we walk on today!
What are Glaciers?
Glaciers are large, thick masses of ice that form on land and get compressed by their own weight over many centuries. Glacier movement and the meltwater can shape landscapes.
How do Glaciers Form and Shape Rocks?
Glaciers move very slowly and are very heavy. As glaciers move across the landscape, they scrape away the earth including layers of rocks and soil. This process exposed and smoothed bedrocks to create how the rocks of Georgian Bay look today. There is evidence of the existence of glaciers all over the Biosphere!
Evidence of Glaciers Right at Our Feet!
Chatter marks are a series of moon or crescent shapes gauges chipped out of bedrock as a result of glacial movement. They show evidence of where glaciers have dragged rocks across other rocks leaving dents in the bedrock.
Glacial striations are long, narrow scratches that appear on the surface of a rock. Gouges and stretches are cut into the rock by the movement of the base of a glacier moving across the rocks. Most glacial striations are long, narrow and straight and often can be several meters in length.
Erratics are rocks or boulders that look different from the surrounding rock. These rocks were picked up in one location by a glacier and dropped in a new location . Often rocks are carried in glaciers by meltwater and then dropped in areas that seem random. The type, pattern, and age of the rock can sometimes completely differ from the rocks in the new location it was left.
What Happens to all the Water When Glaciers Melt?
Glaciers melt and move soil and rocks with their meltwater to create the rock formations we see today. So, what happens to all of the water when glaciers melt?! The meltwater creates lakes and bodies of water! This is how Georgian Bay – Mnidoo Gamii was created. Many lakes in the GBB region were also formed by glaciers.
Anishinaabek Knowledge and Glaciers
Some rocks formed by glaciers have cultural significance. Erratic rock formations often have cultural significance as they are considered evidence of thunderbirds that have dropped these rocks to create landmarks or sacred locations. A rock located near Shawanaga First Nation in Shawanaga Bay called “Turtle Rock” is a significant location as it looks like a Turtle as you are going by on the water. Many Anishinaabek stop to offer tobacco, food, and water to ensure calm weather and travel on the Georgian Bay. This rock formation is evidence of glaciers. There are often no pictures of these locations as they are sacred.
Glaciers beyond the Biosphere
There are glaciers in Canada today! The Athabasca Glacier is located along the British Columbia and Alberta border. It is a part of the Columbia Icefield. There are many ways you can see this glacier as it is located in Jasper National Park. This glacier is shrinking or retreating due to a number of factors. One of the major factors is climate change. With warmer temperatures and decreased snowfall, glaciers are melting much faster than ice can accumulate. Sea levels are also rising due to the melting of glaciers.
Go find some evidence of glaciers! Look for some rocks and find erratics, chatter marks and glacial striations. All over Georgian Bay, there are many examples and evidence of glaciers from billions of years ago. Record your findings with a Nature Notebook or camera!